The technique conventionally used in communication systems having channel conditions with low reliability and varying with time is to perform error correction based on an Automatic Repeat Request (ARQ) system and Forward Error Correction (FEC) technique, and called hybrid ARQ (HARQ). When an error is detected by well-used Cyclic Redundancy Check (CRC) , a receiving section in the communication system requests a transmitting section to retransmit a data packet that is erroneously received (for example, Non-patent Document 1 and Non-patent Document 2).